This post is more than 5 years old
31 Posts
0
4246
Disk Array Layout
Hello,
Our current setup is as follows:
VNX5100
1 x DPE (15 sas drives - 4 for OS)
1 x DAE (15 sas drives)
1 x DAE (2 sas drives)
We are using the array for a VMware server farm and was wondering what a recommended configuration could be to minimize downtime in case of a lost DAE:
For example moving the disks:
dpe - 10 disks
dae - 9 disks
dae - 9 disks
Then create some RAID groups that use disks from each tray????? I know by default the RAID groups take the disks from the same tray.
Thanks
dynamox
1 Rookie
1 Rookie
•
20.4K Posts
0
January 15th, 2012 18:00
if you look in VNX best practices document, there is actually a section for vertical provisioning. Other then some corner cases, it's not something that you MUST do and if you use virtual pools it does not matter anymore.
dynamox
1 Rookie
1 Rookie
•
20.4K Posts
1
January 13th, 2012 19:00
take a look at these two papers, they might give you some ideas
White Paper: EMC Unified Storage System Fundamentals for Performance and Availability
VNX Best Practices for Performance and Availability 31.5
dynamox
1 Rookie
1 Rookie
•
20.4K Posts
1
January 15th, 2012 17:00
i started with clariion back in the days (fc4700) and have never lost a DAE.
Jingyi1
199 Posts
0
January 15th, 2012 17:00
I strongly recommend to create Raid Group cross as many DAEs as possible. I have seen so many times the whole DAE drives dropped not ready due to LCC/Power/Loop issue. It's not a smart way to put all your eggs in same basket.
hxman101
31 Posts
0
January 15th, 2012 18:00
And the best practices guides mentioned above doesn't really say horizontal provisioning (default) of disks is NOT recommended.
Jingyi1
199 Posts
0
January 15th, 2012 19:00
When I was in Symmetrix support team, I saw the whole DAE failed every day for variety of reasons. Sometimes the whole bus failed which includes 2 or 3 DAEs. Because Symmetrix always keep another datacopy on other bus, customer won't experience DA. I am always wondering why CLARiiON would select drives in the same DAE to form Raid Group by default. You can follow EMC BP. But if I have a CLARiiON, I won't create Raid Group on that way.
dynamox
1 Rookie
1 Rookie
•
20.4K Posts
0
January 15th, 2012 20:00
each DAE is connected to different buses on each SP, just like DAE is connected to different DA on the Symm ..so how is that different ?
dynamox
1 Rookie
1 Rookie
•
20.4K Posts
0
January 15th, 2012 21:00
and if you put your raid group members in different DAEs and you have mutlipe drive failures in your RG you won't exprience DU ?
dynamox
1 Rookie
1 Rookie
•
20.4K Posts
0
January 15th, 2012 21:00
well aware of private RG, do you think they are spread over multiple DAEs. No
dynamox
1 Rookie
1 Rookie
•
20.4K Posts
0
January 15th, 2012 21:00
DAE on Clariion is connected to one bus on SPA and one bus on SPB, so even iif you have two disk in the same DAE, they are available to both buses.
Jingyi1
199 Posts
0
January 15th, 2012 21:00
Keep in mind pool is also comprised of multiple Raid Groups. If you lose 2 disks in the same raid group, you will face Data Unavailable. Not spreading Raid Groups to multiple DAE will have higher chance to encounter dual drive failure.
Jingyi1
199 Posts
0
January 15th, 2012 21:00
The difference is if you create a Raid 1 device, symmetrix will never choose 2 disks in same DA (Bus on CLARiiON).
Jingyi1
199 Posts
0
January 15th, 2012 21:00
What I'm saying is if you spread disks of one raid group to multiple buses, you won't experience DU if you lose the whole DAE. Other than that, I agree with you.
dynamox
1 Rookie
1 Rookie
•
20.4K Posts
0
January 15th, 2012 22:00
ok, we are in agreement
then. I can see losing one LCC but two at the same ..must be some really really bad luck.
SKT2
1.3K Posts
0
March 3rd, 2012 10:00
isn't a given DAE talk/attach to only a single bus? if the DAE itself is available to multiple buses where is the need to distribute buses comes from ! i did not follow the significance of brining up "SP" here..